A method for incorporation into the genome of a target lytic phage of an exogenous DNA sequence, wherein the genome of the target lytic phage includes a first target sequence and a second target sequence, which method comprises: (a) providing a vector containing a phage targeting region comprising (i) a host range determinant of a marker phage, different from the host range determinant of the target lytic phage, and (ii) an exogenous DNA sequence: where the targeting region of the phage is flanked by the first and second flanking sequences homologous to the first and second sequences of the target lytic phage genome； (b) introducing the vector into a first host cell, the host cell of which is a host for the target lytic phage； (c) infecting the first host cell with the target lytic phage； (d) allowing replication and recombination of the phage to take place such that the genome of the target lytic phage is modified； (e) propagating the resulting phage in a second host cell, the host cell of which is a host for the marker phage and not the target lytic phage； and (f) harvesting the resulting phage, such that the genome of the target lytic phage is modified by incorporation into it of an exogenous DNA sequence.Un método para la incorporación en el genoma de un fago lítico diana de una secuencia de ADN exógeno, donde el genoma del fago lítico diana incluye una primera secuencia diana y una segunda secuencia diana, cuyo método comprende: (a) proporcionar un vector que contenga una región de direccionamiento del fago que comprenda (i) un determinante de intervalo de huéspedes de un fago marcador, diferente del determinante de intervalo de huéspedes del fago lítico diana, y (ii) una secuencia de ADN exógeno: donde la región de direccionamiento del fago está flanqueada por la primera y segunda secuencias flanqueantes homólogas a la primera y segunda secuencias del genoma del fago lítico diana； (b) introducir el vector en una primera célula huésped, cuya célula huésped es u
